OFDM will be widely applied in future communication systems as a basic technique for air interfaces of the systems.
A process of transmitting a signal through OFDM involves:                a. Data to be transmitted is modulated and segmented into a block of data symbols; and        b. the block of generated data symbols and a pilot symbol (a common or Dedicated pilot symbol) are modulated and mapped into specified time-frequency locations of a Physical Resource Block (PRB) to obtain a Data Block (DB) corresponding to the data to be transmitted; and        c. The data block is transmitted.        
For transmission of the signal through OFDM, a channel resource is a two dimensional structures of time-frequency and can be divided into one or more PRBs. FIG. 1 is a schematic diagram of a PRB which occupies a part of the channel resource. The PRB includes NT consecutive OFDM symbols in the time domain and NF consecutive orthogonal sub-carriers in the frequency domain. The PRB totally includes NT×NF time-frequency locations.
As can be apparent, data of different users can be transmitted over different orthogonal sub-carriers in an OFDM symbol during transmission of the signal through OFDM to thereby achieve multiplexing and multiple-access of users.
For an OFDM system, there is no multiple access interference in a cell. However in a same frequency network, users of neighbor cells may cause interference to each other if signals are transmitted at the same time-frequency locations. Especially if a user at the edge of a cell is closer to another neighbor cell, then an interference signal from another user in the neighbor cell may be strong so that the user at the edge of the cell may suffer from a degraded quality of communication.